1. Field of the Invention
The invention relates to a wheelset bearing for the wheelset of a rail vehicle having a truck with internally mounted bearing, comprising one bearing housing per side of the wheelset, where the bearing housing encloses the wheelset bearing for a wheel, wheelset bearing and bearing housing are located inside the wheels in the installed state, and a torsion spring which serves as a roll stabilizer and is connected to the bearing housing.
A wheelset in rail vehicles consists of the wheelset axle and the two wheel disks or wheels. Brake disks or drive components can also be mounted on the wheelset axle. The wheelset is supported in the truck by the wheelset bearing. In railroad vehicles, the two wheels of a wheelset are usually fixedly connected to the axle on account of the sinusoidal trajectory described and co-rotate therewith. For this reason reference is made in this context to wheelset and accordingly to wheelset bearing. The wheelset bearings guide the wheelset laterally in the truck and also transmit longitudinal forces when the wheelset is driven or braked. The wheelset bearing is typically implemented as a roller bearing that is seated in the wheelset bearing housing and supports the wheelset.
2. Description of the Related Art
In rail vehicles, but also in other vehicles, the car body is usually spring-mounted relative to the wheelsets by way of one or more suspension stages. The centrifugal acceleration acting transversely to the direction of travel and consequently to the vehicle longitudinal axis such as occurs during curving is responsible, due to the comparatively high center of gravity of the car body, for the tendency of the car body to tilt with respect to the wheelsets toward the outside of the curve, in other words, therefore, to execute a rolling motion about a roll axis parallel to the vehicle longitudinal axis. Above certain threshold values such rolling motions detract from the ride comfort on the one hand. On the other hand, they entail the risk of infringing the permissible minimum clearance outline as well as, with regard to derailment safety, provoking unacceptable unilateral losses of wheel load.
In order to prevent this, stabilizing mechanisms in the form of devices known as roll stabilizers are generally used. Their function is to oppose the rolling motion of the car body with a resistance in order to lessen said motion, while the rising and falling motions of the car body with respect to the wheelsets or the chassis are not to be impeded. Running gear or chassis is the term applied to that part of a rail vehicle by which the vehicle travels and is guided on the rails. A running gear having two or more wheelsets arranged in a frame is referred to as a truck.
Such roll stabilizers are known in a variety of hydraulically or purely mechanically acting implementations. Use is often made of a torsion shaft, also referred to as a torsion bar or torsion spring, extending transversely to the longitudinal direction of the vehicle, as is known for example from DE 198 19412 C1.
Seated on the torsion shaft on both sides of the vehicle longitudinal axis are levers that are mounted in a rotationally fixed manner and extend in the vehicle longitudinal direction. These levers are in turn connected to control arms or connecting rods that are arranged kinematically parallel to the suspension devices of the vehicle. When the springs of the suspension devices of the vehicle are compressed, the levers seated on the torsion shaft are set into rotational motion via the control arms to which they are connected. If, during negotiation of curves, a rolling motion occurs with the suspension devices on either side of the vehicle experiencing different degrees of spring deflection, this results in different angles of rotation of the levers seated on the torsion shaft. The torsion shaft is accordingly subjected to a torsional moment which, depending on its torsional stiffness, it compensates for at a certain torsional angle by a counter-moment resulting from its elastic deformation, thus preventing a further rolling motion. On rail vehicles fitted with trucks, the stabilizing device can in this case be provided for the secondary suspension stage, i.e., acting between a chassis frame and the car body. Equally, the stabilizing device can also be utilized in the primary suspension stage, i.e., operating between the wheel units and a chassis frame, as in DE 19819412 C1.
Inside bearing trucks, where the axle bearings and the frame components are located between the wheels or wheel disks, have smaller dimensions transversely to the direction of travel than outside bearing trucks, which means that inside bearing trucks provide a correspondingly smaller base for supporting the primary suspension stage. If the stiffness ratings of the primary springs are similar to those in the case of outside bearing trucks, the roll angle increases and the vehicle can come into conflict with the kinematic gauge. The kinematic gauge defines the maximum space envelope that can be occupied by vehicles to ensure they remain within the infrastructure minimum clearance outline. For this purpose, the maximum possible movement of the vehicle is considered, with both lateral and vertical vehicle motions being taken into account, which are calculated under different load conditions based on the vehicle geometry and suspension characteristics.
One possibility of roll stabilization is to install a primary roll stabilizer (comprising torsion springs, levers, tie/push rods and a mounting for the torsion spring on the truck frame) between the wheels, even in the case of inside bearing trucks, as is shown specifically in DE 19819412 C1. However, such roll stabilizers, with the various components and with the mounting on the truck frame, constitute a technically complex solution.
Another possibility for reducing the roll angle and consequently for increasing the suspension anti-roll stiffness is to increase the primary suspension stiffness rather than to use a roll stabilizer. However, this has the disadvantage that higher accelerations occur on the car body, thus reducing the ride comfort for any passengers.